package cn.dai.Reflection.demo;

import org.junit.Test;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * @author ArkD42
 * @file 1 - Java基础语法
 * @create 2020 - 04 - 23 - 11:16
 */
public class ReflectionTest2 {

    @Test
    public void fieldCall() throws NoSuchFieldException, IllegalAccessException, InstantiationException {
        // 类类型对象
        Class<Animal> animalClass = Animal.class;

        // 获取指定字段 java.lang.NoSuchFieldException: name 访问失败 字段是private 不推荐使用
        //Field name = animalClass.getField("name");

        Field name = animalClass.getDeclaredField("name");

        // name.set(animal,"阿伟"); 设置异常，需要解放权限访问
        // java.lang.IllegalAccessException: Class cn.dai.Reflection.demo.ReflectionTest2 can not access a member of class cn.dai.Reflection.demo.Animal with modifiers "private"
        name.setAccessible(false);

        // 生成空参对象
        Animal animal = animalClass.newInstance();

        // 字段实例 调用方法 注入对象和字段注入
        name.set(animal,"阿伟");

        // 获取对象的此字段
        Object o = name.get(animal);
        System.out.println(o);
    }

    @Test
    public void methodCall() throws IllegalAccessException, InstantiationException, NoSuchMethodException, InvocationTargetException {
        // 类类型对象
        Class<Animal> animalClass = Animal.class;

        // 指定本类的某一方法，第一参数：方法的名字，可变参数，参数列表顺序的参数类型
        Method show = animalClass.getDeclaredMethod("show", String.class);

        // 生成实例
        Animal animal = animalClass.newInstance();

        // 以防万一 解开访问权限
        show.setAccessible(true);

        // 调用方法
        Object waKanDa = show.invoke(animal, "瓦坎达");

        System.out.println(waKanDa);
    }

    @Test
    public void staticMethodCall() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        // static void haha(){ System.out.println("adasdasdsad"); }

        Class<Animal> animalClass = Animal.class;

        Method haha = animalClass.getDeclaredMethod("haha");
        haha.setAccessible(true);

        // 静态的直接调用运行时类的实例,这里是一个空参方法，只要实例一个参数即可
        Object invoke = haha.invoke(animalClass);
    }

    @Test
    public void constructorCall() throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
        Class<Animal> animalClass = Animal.class;

        // 根据重载的特性，只要参数不一样，或者个数不一样，都可以找到
        Constructor<Animal> declaredConstructor = animalClass.getDeclaredConstructor(String.class);

        declaredConstructor.setAccessible(true);

        // 创建！
        Animal animal = declaredConstructor.newInstance("杰哥");
        System.out.println(animal);
    }
}
